Dishwashing machine



April 1, 1952 L. A. LOEB 2,5915080 DISHWASHING MACHINE v Filed June 13, 1944 5 Sheets-Sheet l April 1, 1952 1.. A. LOEB DISHWASHING MACHINE 5 Sheets-Sheet 2 Filed June 13, 1944 ll/ll!!! arr/0mm April 1, 1952 LOEB 2,591,080

DISHWASHING MACHINE Filed Jun 15, 1944 5 Sheets-Sheet 5 April 1, 1952 A. LOEB DISHWASHING MACHINE 5 Sheets-Sheet 4 Filed June 13, 1944 April 1, 1952 L. A. LOEB 2,591,080

DISHWASHING MACHINE Filed June 13, 1944 5 Sheets-SheetS Patented Apr. 1, 1952 UNITED STATES PATENT OFFICE 2,591,080 DISHWASHING MACHINE Lawrence A. Loeb, New Haven, Conn. Application June 13, 1944, Serial No. 540,033 2 Claims. (01. rat-139) This invention relates to dishwashing machines and more particularly to a household dishwashing machine of cabinet style'which may be employed in the usual household kitchen.

It is contemplated by the present invention to provide a washing machine of improved construction and operation as compared to those in use at the present time. As illustrated and described, the improvements are applied to a dishwashing machine which will be controlledma-nually in that it will be provided with a control element moved manually to a plurality of stations or positions. For example, the handle or control member may normally stand in .the OE position, corresponding to that in which the machine is at rest. It may then be moved to the "fill" position in which hot and cold water inlets are opened and the drain closed, so that the tub or tank will be filled with the desired supply of water of the proper temperature. The handle may then be moved to the on position in which the dishwashing operation is effected. In the present instance, the Washing of the dishes is accomplished by the recirculation of the water in the tank by a motor-driven pump. That is to say, the warm water is drawn from the tank by the pump and by means of a suitable sprayer sprayed over the dishes to cleanse them, the pump and spray jet taking the place of a rotor or agitator employed in the tank in some of the devices in use at the present time.

After the dishes have been cleansed, the control member may then be moved to the rinse position in which the drain is held in closed position and the hot water inlet alone opened to permit clean hot water to enter the tank for rinse purposes. During this time, an auxiliary or overflow drain, which is provided, will serve to prevent the water in the tank from rising above a predetermined level, the excess water being drawn from the bottom of the tank in order to drain from the latter principally the water used in the washing operation. During this rinse operation, the water in the tank will again be recirculated by the pump to effect the rinsing of the dishes. The control member may then be turned to off or original position after the rinsing position is finished, which will end the dishwashing cycle and the dishes may be removed from the machine and a new supply provided for a subsequent operation.

It is sometimes inconvenient in dishwashing machines in present use to place the dishes in and remove them from the dish rack within the tank, which rack is usually located near the bottom of the tank. In the present device, this cessible to the operator.

lower dish rack is'mo'v'able so that it may be raised to an elevated position-conveniently. ac-

This raising of the dish rack is effected hydraulically by means of the same pump which recirculatesthe water in the tank, the arrangement being such that the outlet of the pumpiinay be connected to the hydraulic lifting -deviee.to raisesthe latter, which would remain in'rai'sed position'until a valve-is operated to permitthe venting :ot the lifting device and thus'allow the r'ackto descend by its Owhwight; f1. .1 There is also provided in the present device? a soap-dispensing apparatus-consisting :of a soap container, which maybe filled at intervals and which will be automatically operated by the movement of the control member or handle .to discharge into the tank a proper supply of soap for one operation, whereby the'operator, after placing the dishes in the rack while it is. heldin a raised position in the .tank, needs only to lower the rack and then turn the handle or control member to the various positions in order to fill the tank with a supply of water of theproper temperature, "admit a supply of soap to this water, wash-the dishes by a spray jet from recirculation of the water in the tank, rinse the dishes while a spray of hot water. is being admitted to the tank, then drain the tank, all by movement of the single control member.

One object of the prese t invention is the provision of a dishwashing machine of improved operation.

A still' further object of the invention is to provide a rotating jet or spray head by means of which the water in the tank of the machine is recirculated and drawn over the dishes during the cleansing operation.

To these and other ends the invention relates to the novel features and combinations of parts to be hereinafter described and claimed.

In the drawing:

Fig. l is a sectional view of a washing machine embodying my invention, certain parts being shown diagrammatically;

. Fig. 2 is a sectional view on line 2-4 of Fig. l; Fig. 3 is a top plan view of the parts shown in Fig.

Fig. 4 is a detail view of the motor control switch;v

Fig. 5 is asectional view on line 5-5 of Fig. 2;

Fig. 6 is a top plan view of the spray head at the lower portion of the tank;

Figs. 7, 8, 9 and 10 are diagrammatic views showing the positions orcertain of, the parts in various stages in the operation of the machine;

Fig. 11 is a partial sectional view of the front portion of the machine showing the soap dispenser;

Fig. 12 is an enlarged sectional view on line IZ -IZ of Fig. 11;

Fig. 13 is a sectional view on line I3-I3 of Fig. 11; and

Fig. 14 is a partial sectional view showing a modified form of dish rack raising means.

To illustrate a preferred embodiment of my invention I have shown a dishwashing machine comprising a cabinet I having mounted therein a tank II, the tank being provided with a cover I2, which may be removed or opened to permit access to the interior of the tank for loading the dishes therein preparatory to a washing operation. It will be noted that the front or left end wall of the tank as shown in Fig. l is spaced from the front of the cabinet I0. and within this space is mounted a control panel I3 upon which is carried the control mechanism, as will be hereinafter described.

Projecting upwardly through the bottom of the tank and secured therein is a hollow standard I4 upon which is slidably mounted a tubular member I to the lower end of which are secured radial arms I5 upon which is removably supported the lower dish rack, designated generally by the numeral I5. The standard I4 extends through the bottom I! of the tank and may be suitably sealed against leakage as shown at I8.

The tank is provided with a drain 20, having at the upper portion thereof a well 2| in which is mounted the drain valve 22. This valve is provided with a stem 23, the lower end of which is connected to a lever 24 pivoted at 25, so that when this lever is oscillated in a vertical direction about its pivot, the valve 22 will be raised and lowered to open and close the drain. A spring 21 is secured at one end of the lever 24 and at its other end to a collar 28 on the drain pipe, which spring normally acts to hold the drain valve in open position, as shown in Fig. l.

The tank is supplied with water by means of hot and cold water, pipes 30 and 3|, which lead to the usual domestic supplies of hot and cold water. These pipes are directed into valve casings 32 and 33, respectively, in each of which is mounted a valve 34 (only one of these valves being shown). Each of the valves 34 may be actuated by a lever 35 pivoted at 36 at one end, and having pivoted to the other end a link 31. To one of the links 31 is pivoted a lever 38 controlling the hot water valve, while to the link 31 of the cold water valve is pivoted a lever 38, so that the valves 34 will be controlled by movement of the levers 38 and 38. The levers 38 and 38 are provided, respectively, with springs 39 and 33*, these springs tending, as shown in Fig. 2, to hold the free ends of the levers downwardly and thus hold the valves 34 in closed position.

Pipes 42 and 43 lead from the valve casings 32 and 33, respectively, to a T 44 (Fig. 1) from which a. pipe 45 leads to a spray head 46 upon the inner wall of the tank II, this spray head being provided with a plurality of slotted openings 41 and 48. It will be noted that the opening 41 is substantially horizontally disposed, while the slot 43 is inclined downwardly. With this construction, the hot and cold water supplied to the tank will be mixed in the T 44 and will be supplied to the tank in a plurality of sprays or jets, one being directed downwardly toward the dishes in the rack I5 and the other being directed across the tank so as to strike thedishes upon the far side of the rack.

Within the tank II and adjacent the bottom thereof is rotatably mounted a spray head 50 of hollow formation and having provided on its upper surface a plurality of elongated openings 5| obliquely directed so as to cause the spray head to rotate when water under pressure is expelled through these openings. This spray head is rotatably mounted upon a collar 52 supported upon the bottom of the tank and which surrounds the standard I4 previously referred to. Water is delivered to the spray head through an inlet pipe 53, which pipe leads to a valve casing 54 having a rotary valve member 55 therein, the valve having a port 55 which connects the pipe 53 with a pipe 51 leading to the outlet of a pump 58 driven by a motor 53. The inlet of the pump issupplied through a pipe 69 leading to a port GI in the valve 55, which in the position of the valve shown in Fig. 1 connects the pipe 68 to a pipe 62 leading to the well 2I at the bottom of the tank. It will be apparent that in this position of the valve and associated parts, when the motor 59 is in operation and the pump 58 is driven, water will be drawn from the tank II (the valve 22 presumably being closed) through the pipe 62 into the pump 58 and discharged through the pipe 51, and the pipe 53 into the spray head 50', which will be caused to rotate and throw jets of this water over the dishes in the tank to cleanse and rinse them, as this action takes place during both the washing or cleansing and rinsing operations.

Provision is made for rotating the valve 55 by means of a member 63 connected thereto, to

. which member is pivoted a link 64, this link as shown in Fig. 3 being connected at its upper end to a lever 55 pivoted to the cabinet at 66, which lever projects without the cabinet, as shown a 61, where it may be manually oscillated to move the link 54 in a vertical direction. The movement of the valve 55 may be limited by the pin 58 and slot 69.

Within the standard I4 is mounted a pipe III connected to a pipe II leading into the drain 20, the pipe I0 being sufficiently small to be spaced from the walls of the hollow standard I4, so that water may enter the interior of this standard around the pipe and be discharged into the upper end of the member I5. Between this latter member and the standard I4 is provided suitable packing '12 to confine this water above the upper end of the standard I4. With this construction, it will be apparent that when water is admitted to the standard I4 through a connection I3 at its lower end and a pipe 14 leading into the connection [3, the pressure of this water upon the upper closed end of the hollow member I5 will cause the latter to rise upon the standard I4 and carry with it the dish rack I6, so as to elevate the rack and bring it to a level near the top of the tank (the cover I2 being opened) so that it may be conveniently loaded with dishes. To prevent an excess of pressure in the member I5 a valve 15 is provided at the upper end of the pipe I0, which valve will be lifted from the mouth of this pipe by the chain 16 connected to the valve and to the upper closed end of the member I5, so that when the latter member reaches a point limited by the length of the chain 15, the valve I5 will be raised from its seat and permit the water in the upper end of the member I5 to drain downwardly through the pipe I0 into the drain 20 and prevent further raising of the dish rack. As will be presently explained, the lowering of the dish rack is eifected by venting the pipe-I4 5 and permitting the parts to descend under their own weight.

The pipe 14 leads to a port 80 in valve 55 in the position of this valve shown in Fig. l, and is by this port connected to a tube 8I leading into the drain 20. This is the position occupied when the member I5 is vented to the drain to allow the lowering of the dish rack. When, however, the valve 55 is moved in a clockwise direction as permitted by the pin 68 and slot 69, the outlet pipe 51 of the pump =58 will be connected by the valve port 56 to the pipe I4 leading into the standard I4. With the motor 59 and pump 58 in operation, in this last position of the parts, the water delivered by the pump through the pipe 51 will pass into the standard I4 and raise the rack I6. For this raising operation, the motor 59 may be controlled by the switch 82, which may be manually operated at the outside of the cabinet so that after the valve 55 has been turned to position to connect the pump with the interior of the standard I4, the operator may start the motor so as to raise the dish rack and, at the end of the operation, stop the motor to hold the dish rack in raised position during the loading of dishes thereinto.

Mounted within the cabinet and between the front wall thereof and the front wall of the tank or tub II is a soap dispenser comprising a container 84 having a swinging door 85 at the front of the cabinet, which may be swung outwardly and permit the filling of the container. In its lower end, the walls of the container converge as shown at 86 and 81 (Fig. 12), and in this portion of the container is mounted a slide 88 having an opening 89 therein into which opening the soap descends when the slide is in the position as shown in Fig. 12, the soap being contained therein by the bottom 90 of the container itself. The lower portion of the container is provided with a laterally ofiset chute 9I with which the opening 89 is adapted to register when the slide 88 is shifted to the right from the positions shown in Figs. 12 and 13. The slide is provided with a portion 92 extending beyond the container, to which is connected a spring 93 suitably tensioned to normally hold the slide in closed position or in the position shown in Fig. 12. A lever 90 pivoted at 95 is provided at its lower end with a slot 98 embracing a pin 91 upon the portion 92 of the slide, so that when the lever is oscillated, the contents of the opening 89 in the slide drop through the chute 9|, which as shown in Fig. 11 communicates with the tub II through the opening 98. When the slide is moved to the discharging position just described, the bottom of the container will be closed by the part 99 of the slide so as to retain the remainder of the contents of the container in the latter until the slide is returned by the spring 93 and again permits a quantity of soap to descend into the opening 89. This portion 89 of the slide thereby constitutes a measuring device to deliver a measured quantity of soap to the tank of the machine.

The control mechanism is shown more particularly in Figs. 1 to 5 of the drawing and comprises a disk-like member I secured to a shaft IOI rotatably mounted in the control panel I3 and extending without the case or cabinet I0 where, upon its extended end, is secured a control knob I02. The shaft passes through a sleeve I 00, and a compression spring I is mounted between the end wall of this sleeve and a washer I06 mounted on the shaft and held in place by the pin I01. With this arrangement the shaft may move inwardly against the tension of spring I05, but will be normally held in the position illustrated in Fig. 5. The inner face of the sleeve I04 is provided with recesses I08 at intervals of these recesses being adapted to receive a rib I09 on the hub IIO of the disk I90 so that the disk will be yieldably held in one of four positions about its axis of rotation. It will be understood that the rib I09 is permitted to move out of the recess I08 against the tension of spring I05 in order to permit free rotation of the disk, except for the tendency of the latter to be held at one of the four stations corresponding to one of the four steps in the operation of the device.

Secured at diametrically opposite points to the disk I00 are outwardly projecting arms H2 and H3 having long and short rearwardly extending pins H4 and H5 carried thereby. It will be noted from Fig. 3 that pin H4 is adapted to lie below both of the arms or levers 33 and 38 while the pin H5 is not of sufficient length to reach the lever 38- and, therefore, will operate the lever 38 onl'y.when the control disk I0!) is rotated.

The control disk is also provided with a second pair of rearwardly extending pins IIS and H7 located at substantially 90 apart on the disks I00, which pins lie below and are adapted to actuate a lever II8 pivoted at H9 and normally urged downwardly by a spring I20. The lever I I 8 has mounted thereon a mercury switch I2 I of the usual form, this switch, when tipped by the oscillation of the lever IIO, making contact to supply current to the motor 59 to set this motor in operation, whereby the starting of the motor will be effected automatically upon the turning of the control disk I00. It may here be stated that the manually operated switch 82, which also controls the motor to effect the raising of the rack I8, will be connected to the motor in parallel with the switch I2I so that the operation of either of these switches will start the motor independently of the other.

The disk I00 is also provided with a stud I22 designed to contact the lever 90 once during each revolution and operate the slide 88 to deliver a predetermined quantity of soap to the container for the washing operation, this engagement taking place at the first movement of the controlling disk from its ofi position. Also connected to the stud I22 is an extensible spring I23 secured at its other end to a link I24. The other end of this link is secured to the lever 24, which oprates the drain valve 22. The spring I23 provides an extensible connection between the disk I00 and the drain valve so that after the drain valve is closed, the disk can be rotated through its further phases of operation and drain valve held in closed position.

Also leading from the'bottom of the tank I I is an overflow drain I26 which communicates with the pipe I I. It will be noted from Fig. 1 that the pipe I28 is reversely curved to extend above the bottom of the tank so that it empties into the pipe II at a point above the bottom of the tank in order to maintain a certain level of water in the tank. The pipe-'II is continued upwardly beyond the pipe I26 and is left open at the top, as shown at I21, so as to prevent a syphoning action of the water from the tub when the over-flow drain becomes operative, which it will do during the rinsing operation, as will be hereinafter described.

The operation of my device is as follows Referring particularly to Figs. 7 to 10, the

2130. force water into the 7 ed position of the parts is that shown in Fig. I in which the drain valve is held in open position by the spring 21, and the levers 38 and 38 are held down by the springs 39 and 33 so that the hot and cold water valves are closed and the slide 88 of the soap container is in the position as shown in Fig. 12. The disk I is then given a quarter turn in a clockwise direction to the fill position, shown in Fig. 8. In this position the drain valve is closed by the link I24. The valve levers 38 and 38 are raised by the pin I I4 to admit hot and cold water into the tub. During this movement the slide 88 is moved to the right from the position shown in Fig. 12 to deliver a, measured quantity of soap to the tank so that during this operation the drain valve is closed and hot and cold water and soap are admitted to the The disk I00 is then turned through a further quarter revolution when a sufiicient amount of water has been admitted to the tank, which is the washing or operating position of the parts shown in Fig. 9. This movement is permitted by the extension of the spring I23, the drain valve still being held closed. During this movement, the valve levers 38 and 38 are released and drawrrto closed position by their springs 39 and 39, thus shutting ed the admission of water. The pin II I picks up the arm H8 and raises this arm against the tension of the spring I20 to tilt the switch I 2i to start the motor 59. The valve 55 will be assumed to be in the position shown in Fig. l, and it will be seen that water will be drawn from the tank by means of the pipe 62 from well 2i and will be forced through pipes '1 and 53 through the rotating spray head 53 to spray this water forcibly upon the dishes in the tank and cheat rotation of the spray head by the reaction of the jets of water issuing therefrom.

When the dishes are cleansed, the disk IE0 is moved through a further angle of 90 to the position shown in Fig. 10 of the drawings, which is the rinse position. The drain valve is still retained in closed position and the pin I I5 engages and raises the valve lever arm 38 thus admitting hot water to the tank, the cold water valve remaining in closed position. The switch arm III} will be during this movement momentarily released by the pin Ii! but will be picked up by the pin IIS and will, therefore, continue the operation of the motor to maintain an effective spray upon the dishes, as previously described, to rinse them thoroughly. During the admission of the hot rinse water to the tank, the level of the water therein will be raised sufiiciently to how out of the drain I26 and pipe II. connection of the pipe I25 is made at the very bottom of the tank, this will carry off to a large extent the water used during the washing operation and the dishes will be rinsed in the fresh hot water which is permitted to enter.

When the rinsing operation is complete, the disk I00 is turned to the starting or "off" position shown in Fig. 7. Both hot and cold water valves will then be closed, the action of the motor will be stopped, and the drain valve will be opened to permit the draining of the tub.

By means of the lever 51, the valves 55 may now be rotated through the link 64, and this rotation will serve to connect the pipe I30 to a, pipe I28 leading to the cold water supply. Also the pipe 51, which is the outlet of the pump, will be connected through the port 56 to the pipe I4 leading to the hydraulic lift. The motor may now be started through the manually operated switch 82 standard and thus raise As the the dish rack It to an elevated position so that the dishes may readily .be removed. When it has reached this position, the motor will be stopped by the switch 82, and the pressure in the tubular member I5 will hold the rack in elevated position. If, however, the operator forgets to operate the switch 82 for a moment, the valve I5 will be raised from its seat and permit the water in the member I5 to be vented through the pipe II so that the elevation of the dish rack will be limited by the length of the chain It.

When the dish rack has been reloaded, the valve 55 is rotated to its original position, that shown in Fig. 1, wherein the pipe I4 i connected with the pipe 8I leading to the drain 20 so as to permit the venting of the water from the tubular member I5 and allow the dish rack to descend under the influence of gravity. The parts are now in a position for a subsequent cycle of operatlons.

It be noted that during the admission of water into the tub for the washing operation and also for the rinsing operation, the water sprays into the tub through the spray openings 41 and 48, whichopenings are in the form of narrow slots to permit the efiective spraying of water over the tops of the dishes to give them a preliminary cleansing; and that during the washing and rinsing operation, the rotation of the spray head jets will insure that all of the surfaces of the dishes will be efiectively cleansed by the spray jet which issues therefrom. In Fig. 14 of the drawings I have shown a modified form of hydraulically operated lifting means for the dish rack [5. In this instance the raising mechanism is placed below the dish rack so that it will not be disposed within the tub above the rack, but will be entirely below the latter.

A tubular member I30 projects upwardly through the bottom of the tub and through the rotary spray head 50. Within the member I30 is a piston I3I having packing I32 making tight contact with the tubular member I30. The piston carries at its lower end a rod I33 which extends downwardly from the connection I3 and has an abutment I34 mounted adjustably upon its lower end. Upon the upper end of the piston I3I is supported the rack I6, so that when water under pressure is admitted to the tube I30 below the piston through the connection I3 and pipe I4, the piston will be raised and elevate the dish rack.

In this instance, the motor 59, which drives the pump 58, is controlled by a pair of tiltable mercury switches I35 and I36, which are connected in series so that both switches must be closed to efiect actuation of the motor. The switch I35 is mounted on a link I31 pivoted at I38, the free end of this link extending to a point adjacent the controlling member 54, so that it will be engaged by an abutment I39 on thislever. It will be seen, therefore, that when the lever 64 is raised to rotate the valve 55 and connect the pipe I4 with the outlet 51 of the pump 58, the link .I3I will be raised about its pivot and therefore close the contactsv of the switch I35. The normal position of the switch I36 is shown inFigQ14, and in this position the contacts are closed so that upon actuation of the valve 55 by the member 64, the motor will automatically be set into operation.

The switch I36 is pivotally 1nounted on a lever I40 pivoted at I4I to an arm I42, which may be secured to the connection 13. The lever I40 is provided witha stop I43 engaging the arm I42 to 7,5 .limitthe downward movement of the free end of the lever under gravity, which force normally ,maintains the lever in the position shown in the drawings. The lever I40 is provided with a finger I44 extending to a point adjacent the rod I33 to be engaged by the abutment I34 when the dish rack I6 is raised by the piston I3I and reaches a point adjacent the limit of its upward movement. It will be seen, therefore, that further upward movement of the rod I33 will swing the lever I40 about its pivot MI and thus break the contacts of the switch I36 to stop the motor. Therefore, the motor will be automatically stopped when the dish rack is raised to a predetermined elevated position.

It will be seen, therefore, that when the dish rack is in elevated position, the switch I35 is closed and the switch I36 opened. When the member 64 is again operated to return the valve to its original position (as shown in Fig. 14), the link I31 will drop and again break the contacts of the switch I35. In this position, the connection I3 is in communication with the drain pipe 20 and the dish rack and piston I 3| will descend. With the descent of the rack, the lever I40 will again drop due to the action of gravity and close the switch I36. The motor 59 will not be started, however, due to the fact that the switch I35 is open. However, the parts are in position for again starting the motor when the member 64 is again raised to rotate the valve 55.

It will be understood that the control of the motor 59 by the switches I35 and I36, automatically operated upon raising and lowering of the dish rack I6, is employed in addition to the control of the motor by the mercury switch I2I to effect the washing and rinsing of the dishes.

While I have shown and described a preferred embodiment of my invention, it will be understood that it is not to be limited to all of the details shown, but is capable of modification and variation within the spirit of the invention and within the scope of the claims.

What I claim is:

1. A dishwashing machine comprising a tub, a standard projecting upwardly from the bottom of the tub, a dish rack, means for supporting the dish rack on said standard in a position spaced from the bottom of the tub, a hollow sprayer 10 head, means on the bottom of the tub for supporting said sprayer head for rotation about said standard, and means to draw water from the tub and force it through said sprayer head toward the dish rack.

2. A dishwashing machine comprising a, tub, a standard projecting upwardly from the bottom of the tub, a dish rack, means for supporting the dish rack on said standard in a position spaced from the bottom of the tub, a hollow sprayer head, means on'the bottom of the tub for supporting said sprayer head for rotation about said standard, and means to draw water from the tub and force it through said sprayer head toward the dish rack, said dish rack being slidably mounted on said standard.

LAWRENCE A. LOEB.

REFERENCES flTED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,292,495 Lutolf Jan. 28, 1919 1,339,079 Waldref May 4, 1920 1,434,887 Gruner Nov. 7, 1922 1,481,550 Hall Jan. 22, 1924 1,502,863 Merseles July 29, 1924 1,581,528 Anderson Apr. 20, 1926 1,617,021 Mitchell Feb. 8, 1927 1,695,412 Cotterill Dec. 18, 1928 1,757,831 Davidson May 6, 1930 1,867,634 Snyder July 19, 1932 1,908,617 Rodewald May 9, 1933 1,931,410 Hullings Oct. 17, 1933 1,965,870 Walker July 10, 1934 1,980,065 Johnston Nov. 6, 1934 2,044,132 Stoddard June 16, 1936 2,142,902 Kempton Jan. 3, 1939 2,142,924 Stoddard Jan. 3, 1939 2,155,273 Jones Apr. 18, 1939 2,181,983 Voris Dec. 5, 1939 2,276,670 Reifenberg et a1. Mar. 17, 1942 2,315,572 Wilson Apr. 6, 1943 2,339,306 Walker Jan. 18, 1944 2,342,742 Loeb Feb. 29, 1944 2,403,912 Doll July 16, 1946 

